JSON and Highcharts

I'm recently new using JSON and i´m not able to draw any kind of charts from Highcharts. Since last Friday i'm reading and reading over the internet, i'm learning a lot, for sure, but right now i'm desperate. I just want a simple bar and a pie!

From my php file, Json_encode prints something this:

[["January",4],["February",9]]

I think that is the correct format, string with the "" and int without it.

And this is the code that i'm trying (i'm putting the entire example from some web i found):